Cylinder and piston unit

ABSTRACT

A piston is guided for movement in a cylinder and has a piston rod which is coupled with the piston via a pair of juxtaposed grooves provided in the piston and in a portion of the piston rod to define between themselves an enclosed channel in which spherical retaining members are accommodated, with an opening being provided which communicates with this channel and permits the introduction and removal of the spherical members.

Siegel et a1.

[54] CYLINDER AND PISTON UNIT [75] inventors: Heinz Siegel,Bietigheim-Buch; Au-

gust Kraisel, Bittenfeld, both of Germany [73] Assigneei, Robert BoschG.m.h.ii., Stuttgart,

Germany [22] Filed: May 11, 1971 [211 App]. No.: 142,261

[30] Foreign Application Priority Data July 1 l, 1970 Germany ..G 70 26240.7

[52] U.S. Cl. ..92/128, 287/D1G. 5 [51] Int. Cl ..1i"0lb 29/00 [58]Field of Search ..92/128, 255, 29; 287/53 TK, DIG. 5, 52.08; 85/5 B [56]References Cited UNITED STATES PATENTS 5/1949 McCloskey ..285/DlG. 5

LnEjko 2,611,464 9/1952 Rabe ..192/93 C 3,334,773 8/1967 Bimba ..92/l28UX 479,406 7/1892 Dickerson et a1... ..287/DIG. 5 2,714,522 8/1955Becker ..92/128 UX Primary Examiner-Charles J. Myhre AssistantExaminerR. H. Lazarus Anomey-Michael S. Striker [57] ABSTRACT 5 Claims,1 Drawing Figure Patented May 1, 1973 INVENTORS Heinz 5 1565 L 0 05 kRAISEL l'he/r All-army CYLINDER AND PISTON UNIT BACKGROUND OF THEINVENTION The present invention relates generally to a cylinder andpiston unit and more particularly to a cylinder and piston unit having areleasable coupling between the piston and the piston rod thereof.

For various reasons, a detailed discussion of which is not necessary inthe present context, it is frequently desirable to couple the piston rodof a piston in a cylinder and piston unit, releasably with the pistonrather than making it non-removable. According to a construction knownfrom the prior art this can be accomplished by having a bolt extendthrough a portion of the piston and a portion of the piston rod.However, this has been found to be disadvantageous because the boreswhich must necessarily be provided within the piston and in the pistonrod for the passage of the bolt therethrough, evidently weaken thecomponents involved in that they subtract from the cross-sectional areasin which bores must be formed. so that this connection becomessusceptible to breakage.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to overcome the aforementioned disadvantages.

More particularly, it is an object of the present invention to providean improved cylinder and piston unit in which the releasable connectionbetween the piston and piston rod is not possessed of the aforementioneddisadvantages of the prior art.

A concomitant object of the present invention is to provide such animproved unit which is suitable particularly for hydraulic and pneumaticapplications, and which greatly increase the life of the componentsinvolved.

ln pursuance of the above objects, and others which will become apparenthereafter, one feature of the invention resides in a cylinder and pistonunit which, briefly stated, comprises a cylinder and piston which isaccommodated in the cylinder for guided movement therein. A piston rodis also provided and coupling means releasably couples the piston rodwith the piston. The coupling means according to the invention comprisesat least one peripheral groove in the piston, at least one secondperipheral in the piston rod open to the first groove and defining withthe same a peripheral channel, and a plurality of spherical membersaccommodated in this channel and each partially projecting into therespective grooves.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however,

both as to its construction and its method of operation,

together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

I BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a somewhatsimplified partially partial longitudinal section through a cylinder andpiston unit according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing now indetail, it is pointed out that reference numeral 1 identifies a cylinderin which a piston is slidably guided in usual manner, sealingly engagingthe inner circumferential surface of the cylinder 1. The piston isprovided with an axial bore so that it can be pushed onto the innermostend portion of a piston rod 3. A bottom wall 4 closes the cylinder 1 andis provided with a fluid channel communicating with the cylinderchamber.

According to the present invention the piston 2 is provided in its innercircumferential surface bounding its central axial bore with at leastone peripheral groove 5 which is annular and of semi-circularcross-section. In the radial plane of the groove 5 the outercircumferential surface of the piston rod 3 is provided with a similarannular peripheral groove 6 which is also of semi-circular cross-sectionand which defines with the groove 5 a peripheral passage. In thispassage there are accommodated several spherical members 7 which may beof steel or the like and which can be introduced and removed through aradial bore 11 provided in one of the flanges 8 of the piston 2. Theflange 8 in which the bore 11 is provided is also provided with an outercircumferential recess 9 of annular configuration in which there isaccommodated an axially slotted springy piston ring 10 of syntheticplastic material which thus not only provides a sealing action withreference to the inner surface of the cylinder 1, but also covers theradial bore 11. Sealing rings 12 of rubber or similar 'elastomericmaterial are located at both opposite axial sides of the flange 8provided with the ring 10.

To connect the piston od 3 with the piston 2 in releasable manner, it issimply necessary to remove the piston ring 10 and to introduce severalof the spherical elements 7 into the bore 11 so that they can enter intothe channel defined by the grooves 5 and 6 and distribute themselvesaround the circumference of the piston rod and piston, projecting intoeach of the grooves 5 and 6 and thus providing a connection between thepiston 2 and piston rod 3. Thereupon the ring 10 is put in place in thegroove 9 and the channel or bore 11 thereby closed. Conversely toseparate the piston 2 from the piston rod 3, the ring 10 is removed andthe spherical elements 7 are permitted to leave through the bore 11whereupon the piston rod 3 can be withdrawn from the piston 2.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in acylinder and piston unit, it is not intended to be limited to thedetails shown since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this by LettersPatent is set forth in the appended claims.

We claim:

1. A cylinder and piston unit, comprising a cylinder bounded by an innercircumferential surface; a piston in said cylinder for guided movementtherein and having an outer circumferential surface facing said innersurface; a piston rod; coupling means releasably coupling said-pistonrod with said piston, comprising at least one first peripheral groove insaid piston and at least one second peripheral groove in said piston rodopen to said first groove and defining with the same a peripheralchannel; a plurality of spherical members accommodated in said channeland each partially projecting into the respective grooves; an outercircumferential recess provided in said outer surface; a radial bore insaid piston dimensioned to permit passage of said spherical members,said bore having an outer end communicating with said recess and aninner open end communicating with said first groove; and a ring in saidrecess covering said outer open end and in sliding contact with saidinner surface for guiding the movement of said piston in said cylinder.

2. A cylinder and piston unit as defined in claim 1, said piston havingan axial passage bounded by an inner surface provided with said firstgroove, and said piston rod having an end portion accommodated in saidpassage and bounded by an outer surface provided with said secondgroove.

3. A cylinder and piston unit as defined in claim 1, wherein said ringconsists at least predominantly of synthetic plastic material.

4. A cylinder and piston unit as defined in claim 1, wherein said ringconsists of synthetic plastic material.

5. A cylinder and piston unit as defined in claim 1, wherein said ringhas. an axial slit and is composed of a material admitting of resilientradial expansion of said ring with concomitant widening of said slit.

1. A cylinder and piston unit, comprising a cylinder bounded by an innercircumferential surface; a piston in said cylinder for guided movementtherein and having an outer circumferential surface facing said innersurface; a piston rod; coupling means releasably coupling said pistonrod with said piston, comprising at least one first peripheral groove insaid piston and at least One second peripheral groove in said piston rodopen to said first groove and defining with the same a peripheralchannel; a plurality of spherical members accommodated in said channeland each partially projecting into the respective grooves; an outercircumferential recess provided in said outer surface; a radial bore insaid piston dimensioned to permit passage of said spherical members,said bore having an outer end communicating with said recess and aninner open end communicating with said first groove; and a ring in saidrecess covering said outer open end and in sliding contact with saidinner surface for guiding the movement of said piston in said cylinder.2. A cylinder and piston unit as defined in claim 1, said piston havingan axial passage bounded by an inner surface provided with said firstgroove, and said piston rod having an end portion accommodated in saidpassage and bounded by an outer surface provided with said secondgroove.
 3. A cylinder and piston unit as defined in claim 1, whereinsaid ring consists at least predominantly of synthetic plastic material.4. A cylinder and piston unit as defined in claim 1, wherein said ringconsists of synthetic plastic material.
 5. A cylinder and piston unit asdefined in claim 1, wherein said ring has an axial slit and is composedof a material admitting of resilient radial expansion of said ring withconcomitant widening of said slit.